This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. UCSF Chimera is the molecular modeling package being developed at RBVI. Eric Pettersen published a paper describing Chimera in "UCSF Chimera--a visualization system for exploratory research and analysis" (J Comput Chem. 2004 Oct;25(13):1605-12). In addition to molecular models, Chimera also handles volumetric data from microscopy and crystallography. Some of these capabilities are described in "Software extensions to UCSF chimera for interactive visualization of large molecular assemblies" (Structure. 2005 Mar;13(3):473-82). Detailed information and extensive documentation on Chimera may be found at http://www.cgl.ucsf.edu/chimera.